With the rapid development of Internet, there have emerged a great number of mobile data multimedia services and various high-bandwidth multimedia services, such as video conference, TV broadcast, video on demand, advertisements, online education, interactive games and the like. These services meet the increasing demands of mobile subscribers on services and bring a new growth point to the business of mobile operators. Compared with common data services, these mobile data multimedia services require multiple subscribers to receive same data at the same time and are characterized by high data volume, long duration, sensitivity to time delay and so on.
In order to use mobile network resources effectively, the 3rd Generation Partnership Project (3GPP) has proposed a Multimedia Broadcast Multicast Service (MBMS) which is a technology for transmitting data from one data source to multiple targets that realizes the share of network (including a core network and an access network) resources, and improves the utilization ratio of network resources, especially the utilization ratio of air interface resources. The MBMS defined by 3GPP is capable of not only realizing multicast and broadcast of full-text low-speed messages but also realizing multicast and broadcast of high-speed multimedia services and providing abundant multimedia services including video and audio.
In a Long Term Evolution (LTE) system, an MBMS can be sent in a hybrid carrier manner, which means that a Unicast service and an MBMS are sent on the same carrier in the manner of time division multiplexing, wherein a sub-frame is the smallest unit of time division multiplexing. A radio frame adopted in the current LTE for carrying an MBMS meets the following relation:SFN mod radioFrameAllocationPeriod=radioFrameAllocationOffset
wherein as the maximum System Frame Number (SFN, that is number of a radio frame defined in the system) in the LTE is specified as 1023, SFNs are ranged from 0 to 1023; the radioFrameAllocationPeriod represents an MBMS single Frequency Network (MBSFN) radio frame period and is valued to be any of {1, 2, 4, 8, 16, 32}; the radioFrameAllocationOffset represents an MBSFN radio frame offset and is valued to be an integer that is greater than or equal to 0 but smaller than a selected value of an MBSFN radio frame period; and the mod represents a modulus operation of SFN to radioFrameAllocationPeriod. The information on the relation met by a radio frame of an MBMS is sent at System Information Block Type 2 (SIB2) of a system message to a terminal. According to the relation above, if the value of the radioFrameAllocationPeriod is 2 and radioFrameAllocationOffset=0, then MBSFN radio frames are obtained as shown in FIG. 1, wherein shadow areas represent system-configured MBSFN radio frames which are radio frames for carrying an MBMS. Furthermore, the system may configure a sub-frame for carrying an MBMS within an MBSFN radio frame, such sub-frame is referred to as an MBSFN sub-frame. The MBSFN frames and MBSFN sub-frames are both referred to as MBSFN resources, and such MBSFN resources form a Multicast Channel (MCH) transmission channel.
It is specified in the disclosed LTE technologies that when a hierarchical architecture is adopted, a Multicast Control Channel (MCCH) of an MBMS is divided into the following two types: a Primary MCCH (P-MCCH) for carrying a primary multicast control signaling and a Secondary MCCH (S-MCCH) for carrying a secondary multicast control signaling; when no hierarchical architecture is adopted, a control channel of an MBMS is referred to as an MCCH and is used for carrying a control signaling of the MBMS. It is also prescribed in the disclosed LTE technologies that scheduling information of one or two P-MCCHs can be indicated in a system broadcast message (BCCH, Broadcast Control Channel), wherein the scheduling information of one P-MCCH is transmitted on a Downlink Shared Channel (DL-SCH) in a single-cell mode, and the scheduling information of the other P-MCCH is transmitted on an MCH in a multi-cell mode. A control signaling related to services in an MBSFN area is carried by a P-MCCH and is used to indicate effective MBMSs in the MBSFN area and other information. If necessary, the P-MCCH can also carry indication information of an S-MCCH to facilitate the finding of the S-MCCH.
In accordance with the description on the disclosed LTE technologies, MBMSs are classified into a single-cell mode and a multi-cell mode, and P-MCCHs are also classified into a single-cell mode and a multi-cell mode. One of the main features of the single-cell mode lies in no support for combination of MBSFNs of multiple cells, while the multi-cell mode is necessarily required to be supportive to combination of MBSFNs of multiple cells. However, according to the description of the latest disclosed LTE technology, an MCCH no longer supports combination of MBSFNs or distinguish between a primary structure and a secondary structure.
It can be seen from above that both the P-MCCH and the S-MCCH sent in a multi-cell mode are required to be carried on multicast resources composed of multicast frames. If MCCHs are neither divided into primary and secondary structures nor sent in a multi-cell mode, then the MCCHs can be carried on unicast resources (namely, a DL-SCH) or multicast resources (namely, an MCH) composed of multi-cast frames.
For any case above, no uniform standard for transmitting a P-MCCH, an S-MCCH or an MCCH has been provided in prior art, thus leading to an extremely random transmission at a system side. In other words, it is necessary for a terminal to make frequent tries in order to receive above-mentioned MBMS control channel (including said P-MCCH, S-MCCH, MCCH), which may cause a terminal to receive randomly, bring higher signaling overheads, and go against power saving of the terminal.